This research will systematically study changes in illicit drug markets (including users and distributors) due to Hurricane Katrina and by the subsequent flooding of New Orleans. Considerable evidence available before Hurricane Katrina documents the existence of vigorous illegal drug markets in New Orleans. In the unprecedented aftermath of Katrina almost the entire population became New Orleans evacuees (NOEs) located in other host communities. In preliminary research, we provide reports from NOEs in New York City who confirm that illicit drug markets were significantly disrupted or changed in the weeks following the hurricane-the availability of crack, heroin, and marijuana declined drastically during that period. This evacuation of a major urban population leads to the specific aims of the proposed research: AIM A (Drug Market Destruction): To examine illegal drug markets in New Orleans before Hurricane Katrina and to document the changes that occurred afterwards. AIM B (Evacuees entry into New Drug Markets): To investigate how NOE drug users locate drugs to use and/or sell in the receiving communities. AIM C (Market Changes): To analyze whether and how NOE drug users/distributors influence changes in illicit drug markets in the receiving communities. AIM D (Reformulation of Drug Markets): As New Orleans is repopulated and rebuilt, to investigate whether and how illicit drug markets reformulate themselves. Professional ethnographers will conduct the research in New Orleans, Houston, and New York City. Ethnographers will make observations of illicit drug markets and complete personal qualitative interviews with 40 respondents at each of the three sites annually. They will also conduct 8 focus groups annually at each site over a four year period;a given focus group will be composed of NOEs who were/are active in a specific illicit drug market (heroin, crack, marijuana, and other substances). Careful analyses and research articles based upon the rich qualitative data will document the impact of the disruption of New Orleans'illicit drug markets, the impact of NOE drug users on the drug markets in the receiving cities of Houston and NYC, and the anticipated reformulation of drug markets in New Orleans. This research will improve scientific understanding of the ways that illicit drug markets function in the wake of a major disaster, and provide important policy guidance about how to further weaken such markets in the future.